Oxidation catalyst heating system, internal combustion engine system, and method for heating an oxidation catalyst device

Abstract

To provide an oxidation catalyst temperature rise system, an internal combustion engine system and an oxidation catalyst device temperature rise method capable of effectively raising a temperature of an oxidation catalyst device during stop of use of the oxidation catalyst device.SOLUTION: An oxidation catalyst temperature rise system includes: an exhaust gas line in which exhaust gas discharged from an internal combustion engine flows; a catalyst casing provided in the exhaust gas line and accommodating an oxidation catalyst device including a plurality of oxidation catalytic elements configured to oxidize exhaust gas; and at least one temperature rise gas piping in which temperature rise gas for raising a temperature of the oxidation catalyst device flows, the at least one temperature rise gas piping disposed in the catalyst casing and disposed between a pair of oxidation catalytic elements disposed adjacent to each other out of the plurality of oxidation catalytic elements.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an oxidation catalyst heating system for heating an oxidation catalyst device, an internal combustion engine system including the oxidation catalyst heating system, and a method for heating an oxidation catalyst device.

Background Art

[0002] An oxidation catalyst device includes an oxidation catalyst for oxidizing exhaust gas discharged from an internal combustion engine. In order to exhibit the performance of the oxidation catalyst (for example, methane oxidation catalyst) included in the oxidation catalyst device, it is necessary to keep the oxidation catalyst device at a relatively high temperature.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] During the use of the oxidation catalyst device, since the heat energy of the exhaust gas introduced into the oxidation catalyst device and the heat energy generated by the oxidation reaction of the exhaust gas are transmitted to the oxidation catalyst device, the oxidation catalyst device is kept at a relatively high temperature. On the other hand, during the stop of using the oxidation catalyst device, the oxidation catalyst device may be cooled by the surrounding outside air or the like and reach the same temperature as the outside air. In this case, at the start of using the oxidation catalyst device, there is a risk that a long catalyst heating time is required until the oxidation catalyst exhibits its performance.

[0005] Patent Document 1 discloses a catalyst for treating ammonia and nitrogen oxides housed in a casing, with an exhaust gas bypass channel provided on the outer circumference of the casing, aligned with the flow direction of the exhaust gas flowing inside the casing. In the invention described in Patent Document 1, the exhaust gas flowing through the bypass channel can keep the outer circumference of the catalyst warm, but the inner circumference of the catalyst may not be kept warm enough, potentially requiring a long heating time for the inner circumference of the catalyst to perform at its best.

[0006] In view of the circumstances described above, at least one embodiment of this disclosure aims to provide an oxidation catalyst heating system, an internal combustion engine system, and an oxidation catalyst heating method that can effectively heat an oxidation catalyst while the oxidation catalyst is out of use. [Means for solving the problem]

[0007] The oxidation catalyst heating system according to at least one embodiment of this disclosure is The exhaust gas line through which exhaust gases emitted from the internal combustion engine flow, A catalyst casing housing an oxidation catalyst device, which is provided in the exhaust gas line and includes a plurality of oxidation catalyst elements configured to oxidize the exhaust gas, The device comprises at least one heating gas piping through which a heating gas for heating the oxidation catalyst device flows, the heating gas piping being located inside the catalyst casing and positioned between a pair of adjacent oxidation catalyst elements among the plurality of oxidation catalyst elements.

[0008] The internal combustion engine system according to at least one embodiment of the present disclosure is The aforementioned oxidation catalyst heating system, The aforementioned internal combustion engine, An internal combustion engine system comprising: a first exhaust gas path switching device configured to switch the path of the exhaust gas discharged from the internal combustion engine, The oxidation catalyst device includes a methane oxidation catalyst configured to oxidize methane contained in the exhaust gas, The internal combustion engine includes a dual-fuel engine capable of operating by switching between a first fuel containing methane in its exhaust gas components and a second fuel not containing methane in its exhaust gas components. The first exhaust gas path switching device described above is The internal combustion engine is configured to guide the exhaust gas discharged from the internal combustion engine to the catalyst casing while the internal combustion engine is operating with the first fuel, and to guide the exhaust gas discharged from the internal combustion engine to the at least one temperature-boosting gas piping while the internal combustion engine is operating with the second fuel.

[0009] A method for raising the temperature of an oxidation catalyst apparatus according to at least one embodiment of this disclosure is: A method for raising the temperature of an oxidation catalyst device configured to oxidize exhaust gas discharged from an internal combustion engine, The oxidation catalyst device includes a plurality of oxidation catalyst elements, each containing a methane oxidation catalyst configured to oxidize methane contained in the exhaust gas. The internal combustion engine includes a dual-fuel engine capable of operating by switching between a first fuel containing methane in its exhaust gas components and a second fuel not containing methane in its exhaust gas components. The aforementioned method for raising the temperature of the oxidation catalyst apparatus is: A first operating step involves introducing the exhaust gas discharged from the internal combustion engine into a catalyst casing housing the oxidation catalyst device while the internal combustion engine is operating using the first fuel, The second operating step involves, while the internal combustion engine is operating using the second fuel, introducing the exhaust gas discharged from the internal combustion engine into at least one heating gas pipe located inside the catalyst casing and positioned between a pair of adjacent oxidation catalyst elements among the plurality of oxidation catalyst elements. ru. [Effects of the Invention]

[0010] According to at least one embodiment of the present disclosure, an oxidation catalyst heating system, an internal combustion engine system, and an oxidation catalyst heating method are provided that can effectively heat up an oxidation catalyst while the oxidation catalyst is out of use.

Brief Description of the Drawings

[0011] [Figure 1] It is a schematic diagram of an internal combustion engine system according to an embodiment of the present disclosure. [Figure 2] It is a schematic diagram of an internal combustion engine system according to an embodiment of the present disclosure. [Figure 3] It is a schematic cross-sectional view of a catalyst casing of an oxidation catalyst heating system according to an embodiment of the present disclosure. [Figure 4] It is a schematic cross-sectional view taken along the line A - B of the catalyst casing shown in FIG. 3. [Figure 5] It is a schematic cross-sectional view taken along the line C - D of the catalyst casing shown in FIG. 3. [Figure 6] It is a schematic cross-sectional view taken along the line E - F of the catalyst casing shown in FIG. 3. [Figure 7] It is a schematic cross-sectional view of a catalyst casing of an oxidation catalyst heating system according to an embodiment of the present disclosure. [Figure 8] It is a schematic cross-sectional view taken along the line G - H of the catalyst casing shown in FIG. 7.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure, but are merely illustrative examples.

[0013] (Internal Combustion Engine System) Each of FIGS. 1 and 2 is a schematic diagram of an internal combustion engine system 1 according to an embodiment of the present disclosure. As shown in FIGS. 1 and 2, the internal combustion engine system 1 includes an oxidation catalyst warming-up system 2 and a first internal combustion engine 11. The oxidation catalyst warming-up system 2 includes a first exhaust gas line 12 through which first exhaust gas, which is exhaust gas discharged from the internal combustion engine 11, flows. The first exhaust gas line 12 forms a flow path for circulating the first exhaust gas and is formed, for example, by a pipe. The internal combustion engine system 1 may further include a first generator 110 that is connected to the first internal combustion engine 11 and generates electricity by the power generated by the first internal combustion engine 11.

[0014] (Oxidation catalyst warming-up system) The oxidation catalyst warming-up system 2 according to some embodiments is mounted on the internal combustion engine system 1. As shown in FIGS. 1 and 2, the oxidation catalyst warming-up system 2 includes the above-described first exhaust gas line 12, an oxidation catalyst device 3, and a catalyst casing 4. The catalyst casing 4 is provided in the first exhaust gas line 12 and is configured to house the oxidation catalyst device 3.

[0015] In the following description, when simply referred to as the upstream side, it refers to the upstream side along the main flow direction of the fluid in the part or region related to the direction description. Similarly, in the following description, when simply referred to as the downstream side, it refers to the downstream side along the main flow direction of the fluid in the part or region related to the direction description.

[0016] (Catalyst casing) The flow direction of the first exhaust gas flowing through the catalyst casing 4 is defined as the first direction RD1. In the illustrated embodiment, the first exhaust gas flowing through the catalyst casing 4 flows from below to above in the vertical direction. That is, in the illustrated embodiment, the first direction RD1 means a direction from vertically downward to vertically upward.

[0017] Figures 3 and 7 are schematic cross-sectional views of a catalyst casing 4 of an oxidation catalyst heating system 2 according to one embodiment of the present disclosure. Figures 3 and 7 show a cross-section of the catalyst casing 4 along a first direction RD1. Figure 4 is a schematic cross-sectional view of the catalyst casing 4 shown in Figure 3, taken along the line AB. Figure 5 is a schematic cross-sectional view of the catalyst casing 4 shown in Figure 3, taken along the line CD. Figure 6 is a schematic cross-sectional view of the catalyst casing 4 shown in Figure 3, taken along the line EF. Figure 8 is a schematic cross-sectional view of the catalyst casing 4 shown in Figure 7, taken along the line GH.

[0018] In the illustrated embodiment, the catalyst casing 4, as shown in Figures 3 and 7, is formed in a rectangular tubular shape extending along a first direction (vertical direction) and includes a casing body 41 having a first internal space 40 through which the first exhaust gas flows from the upstream side to the downstream side in the first direction.

[0019] The oxidation catalyst device 3 is located in the first internal space 40 and extends along a direction intersecting the first direction (in the illustrated example, a horizontal direction perpendicular to the first direction). The first internal space 40 is divided into an upstream side and a downstream side in the first direction by the oxidation catalyst device 3.

[0020] The casing body 41 has a first exhaust gas inlet 42 formed at its upstream end in the first direction for introducing the first exhaust gas into the first internal space 40 from outside the casing body 41. The casing body 41 also has a first exhaust gas outlet 43 formed at its downstream end in the first direction for discharging the first exhaust gas from the first internal space 40 to the outside of the casing body 41.

[0021] As shown in Figures 1 and 2, the first exhaust gas line 12 includes a first upstream exhaust gas line 12A for leading first exhaust gas from the internal combustion engine 11 to the catalyst casing 4, and a first downstream exhaust gas line 12B for leading first exhaust gas downstream in the flow direction of first exhaust gas from the catalyst casing 4. The upstream end of the first upstream exhaust gas line 12A is connected to the internal combustion engine 11, and the downstream end is connected to the first exhaust gas inlet 42 of the catalyst casing 4. The upstream end of the first downstream exhaust gas line 12B is connected to the first exhaust gas outlet 43 of the catalyst casing 4.

[0022] The first exhaust gas flows through the first exhaust gas line 12 and is guided from the first exhaust gas inlet 42 into the first internal space 40. As the first exhaust gas guided into the first internal space 40 passes through the oxidation catalyst device 3, the oxidation of at least one of the exhaust gas components (for example, methane) is promoted by the oxidation catalyst contained in the oxidation catalyst device 3. The first exhaust gas that has passed through the oxidation catalyst device 3 is discharged from the first exhaust gas outlet 43 to the outside of the casing body 41 (first downstream exhaust gas line 12B).

[0023] (Oxidation catalyst device) The oxidation catalyst device 3 includes a plurality of oxidation catalyst elements 31 configured to oxidize the first exhaust gas, as shown in Figures 4 and 5. Each of the plurality of oxidation catalyst elements 31 includes an oxidation catalyst that promotes the oxidation of at least one of the components contained in the exhaust gas (exhaust gas components). In the illustrated embodiment, each of the plurality of oxidation catalyst elements 31 is formed in the shape of a hexahedron (e.g., a cube or a rectangular parallelepiped) having six square faces. Each of the plurality of oxidation catalyst elements 31 includes a methane oxidation catalyst that promotes the oxidation of methane contained in the exhaust gas.

[0024] In order for the oxidation catalyst (e.g., methane oxidation catalyst) contained in the oxidation catalyst device 3 to perform optimally, the oxidation catalyst device 3 needs to be kept at a relatively high temperature. While the oxidation catalyst device 3 is in use, the thermal energy of the first exhaust gas flowing through the first internal space 40 of the catalyst casing 4 and the thermal energy generated by the oxidation reaction of the first exhaust gas are transferred to the oxidation catalyst device 3, thus keeping the oxidation catalyst device 3 at a relatively high temperature. In contrast, when the oxidation catalyst device 3 is not in use, the oxidation catalyst device 3 is cooled by the surrounding outside air, etc., and may reach a temperature similar to the outside air. In this case, when the oxidation catalyst device 3 is started up, a long period of catalyst heating time may be required before the oxidation catalyst can perform optimally.

[0025] (Heating gas piping) The oxidation catalyst heating system 2 further comprises at least one (multiple in the illustrated example) heating gas pipes 5, as shown in Figures 1 and 2. The oxidation catalyst heating system 2 is configured to heat the oxidation catalyst contained in the oxidation catalyst device 3 by heating gas flowing through at least one heating gas pipe 5.

[0026] In the embodiment shown in Figure 1, each of the plurality of heating gas pipes 5 is configured to carry the first exhaust gas discharged from the first internal combustion engine 11 as the heating gas. In the embodiment shown in Figure 2, the internal combustion engine system 1 further comprises a second internal combustion engine 13 different from the first internal combustion engine 11, and a second exhaust gas line 14 through which the second exhaust gas, which is the exhaust gas discharged from the internal combustion engine 13, flows. The internal combustion engine system 1 may further comprise a second generator 130 connected to the second internal combustion engine 13, which generates electricity using the power generated by the second internal combustion engine 13. In the embodiment shown in Figure 2, each of the plurality of heating gas pipes 5 is configured to carry the second exhaust gas discharged from the second internal combustion engine 13 as the heating gas. Note that the heating gas can be any gaseous heat transfer medium capable of heating the oxidation catalyst device 3, and is not limited to the first or second exhaust gas. The heating gas may also be exhaust gas discharged from the main engine, which is an internal combustion engine for propulsion of a ship.

[0027] Multiple heating gas pipes 5 are arranged inside the catalyst casing 4, as shown in Figures 4, 5, and 8, and are positioned between pairs of adjacent oxidation catalyst elements 31 among the multiple oxidation catalyst elements 31.

[0028] In the illustrated embodiment, each of the plurality of heating gas pipes 5 extends in the same direction as the other heating gas pipes 5. Each of the plurality of heating gas pipes 5 is spaced apart in a direction that intersects (orthogonal in the illustrated example) the direction in which the heating gas pipes 5 extend (left-right direction in the figures) when viewed from the first direction RD1, as shown in Figures 4 and 8. Each of the plurality of oxidation catalyst elements 31 is positioned between a pair of adjacent heating gas pipes 5 in a direction that intersects the direction in which the heating gas pipes 5 extend, when viewed from the first direction RD1, as shown in Figures 4 and 8. It is preferable that each of the plurality of oxidation catalyst elements 31 is in contact with the adjacent pair of heating gas pipes 5. The oxidation catalyst elements 31 may be positioned between a pair of heating gas pipes 5 that are spaced apart in the first direction.

[0029] According to the above configuration, the oxidation catalyst device 3 can be heated by the heating gas flowing through the at least one heating gas pipe 5 while the oxidation catalyst device 3 is not in use. Since the at least one heating gas pipe 5 is located between a pair of oxidation catalyst elements 31 that are arranged adjacent to each other inside the catalyst casing 4, the thermal energy of the heating gas flowing through the heating gas pipe 5 can be efficiently transferred to each of the pair of oxidation catalyst elements 31 that sandwich the heating gas pipe 5. As a result, the entire oxidation catalyst device 3 can be heated effectively, and the catalyst heating time required for the oxidation catalyst to perform at full capacity when the oxidation catalyst device 3 is put into use can be shortened.

[0030] In some embodiments, the oxidation catalyst device 3 (oxidation catalyst element 31) described above includes a methane oxidation catalyst configured to oxidize methane contained in exhaust gas. With the above configuration, in order for the methane oxidation catalyst to perform well, it is necessary to keep the methane oxidation catalyst (oxidation catalyst device 3) at a relatively high temperature, but the methane oxidation catalyst can be heated by the heating gas flowing through the heating gas pipe 5 described above. This makes it possible to shorten the catalyst heating time required for the methane oxidation catalyst to perform well when the oxidation catalyst device 3 is first put into use.

[0031] In some embodiments, as shown in Figures 1 and 2, each of the plurality of heating gas pipes 5 described above extends along a direction intersecting the first direction RD1 described above. With the above configuration, each of the plurality of heating gas pipes 5 extends along a direction intersecting the flow direction of the exhaust gas (first direction RD1) flowing inside the catalyst casing 4, so that the thermal energy of the heating gas flowing through these heating gas pipes 5 can be efficiently transferred throughout the oxidation catalyst device 3 located inside the catalyst casing 4. This allows the oxidation catalyst device 3 to be effectively heated.

[0032] In some embodiments, as shown in Figure 5, each of the plurality of heating gas pipes 5 described above consists of a rectangular duct having a rectangular cross-sectional shape with a pair of long sides and a pair of short sides. In each of the plurality of heating gas pipes 5 described above, as shown in Figure 5, each of the pair of long sides 51 and 52 having the long sides of the heating gas pipe 5 is in contact with a pair of oxidation catalyst elements 31 arranged adjacent to the heating gas pipe 5.

[0033] According to the above configuration, each of the outer surfaces of a pair of relatively large long sides 51 and 52 of the multiple heating gas pipes 5 mentioned above is in contact with the oxidation catalyst element 31. Through the pair of long sides 51 and 52 with a large heat transfer area, the thermal energy of the heating gas flowing through the heating gas pipes 5 having the pair of long sides 51 and 52 can be directly and efficiently transferred to each of the oxidation catalyst elements 31 facing the pair of long sides 51 and 52. This allows the oxidation catalyst device 3 to be effectively heated.

[0034] In some embodiments, the above-described at least one heating gas pipe 5 includes a plurality of heating gas pipes 5 that are spaced apart in a direction intersecting the extending direction of the heating gas pipe 5 (left-right direction in the figures) when viewed from a first direction RD1 (in the illustrated example, a direction perpendicular to the extending direction of the heating gas pipe 5, in the up-down direction in the figures). The above-described oxidation catalyst heating system 2 further includes a plurality of partition plates 6, the ends of which are connected to a pair of heating gas pipes 5 that are adjacent to each other in a direction intersecting the extending direction of the heating gas pipes 5 when viewed from a first direction RD1. The plurality of partition plates 6 are spaced apart in the extending direction of the heating gas pipes 5. Each of the plurality of partition plates 6 has one end connected to one of the pair of heating gas pipes 5 and the other end connected to the other heating gas pipe 5.

[0035] In the illustrated embodiment, each of the multiple partition plates 6 is made of a metal plate that extends in a direction intersecting (orthogonal in the illustrated example) the extending direction of the heating gas pipe 5. One end of each of the multiple partition plates 6 in the direction intersecting the extending direction of the heating gas pipe 5 is fixed to one of the pair of heating gas pipes 5 by welding or the like, and the other end in the direction intersecting the extending direction of the heating gas pipe 5 is fixed to the other of the pair of heating gas pipes 5 by welding or the like.

[0036] The first internal space 40 is divided into multiple spaces 400 by the pair of heating gas pipes 5 and multiple partition plates 6 whose ends are connected to the pair of heating gas pipes 5. As shown in Figure 4, the multiple spaces 400 in the first internal space 40 may be spaced apart in the direction in which the heating gas pipes 5 extend, or they may be spaced apart in a direction intersecting the direction in which the heating gas pipes 5 extend.

[0037] Each of the plurality of oxidation catalyst elements 31 is housed in one of the plurality of spaces 400 described above. Each of the plurality of oxidation catalyst elements 31 is supported by at least one of a pair of heating gas pipes 5 or a pair of partition plates 6 that partition the space 400 housing the oxidation catalyst elements 31. Preferably, each of the plurality of oxidation catalyst elements 31 is in contact with each of the pair of partition plates 6 that partition the space 400 housing the oxidation catalyst elements 31. In this case, the thermal energy of the heating gas flowing through the pair of heating gas pipes 5 is transferred from the pair of heating gas pipes 5 to the pair of partition plates 6, and then transferred from the pair of partition plates 6 to the oxidation catalyst elements 31 in contact with the pair of partition plates 6. That is, the oxidation catalyst elements 31 can also be heated by the thermal energy transferred from the pair of partition plates 6, so the oxidation catalyst elements 31 can be heated effectively.

[0038] With the above configuration, an oxidation catalyst element 31 can be housed in each of the spaces 400 partitioned by the pair of heating gas pipes 5 and the multiple partition plates 6, making it easy to position the oxidation catalyst element 31. Furthermore, the oxidation catalyst element 31 housed in the space 400 receives thermal energy from the heating gas flowing through the pair of heating gas pipes 5 via the pair of heating gas pipes 5 and the multiple partition plates 6 surrounding the oxidation catalyst element 31. This allows the oxidation catalyst element 31 housed in the space 400 to be effectively heated throughout.

[0039] When viewed from a first direction RD1, if a combination of a plurality of heating gas pipes 5 arranged at intervals in a direction intersecting the extending direction of the heating gas pipe 5, a plurality of partition plates 6 connected to both ends of these plurality of heating gas pipes 5, and a plurality of oxidation catalyst elements 31 housed in the space 400 separated by these plurality of heating gas pipes 5 and the plurality of partition plates 6 is considered as one stage, then the oxidation catalyst heating system 2 may have a combination of multiple stages arranged side by side in the first direction, as shown in Figure 5.

[0040] (Direction of flow of heating gas through heating gas piping) In some embodiments, as shown in Figure 4, each of the multiple heating gas pipes 5 described above is configured such that the heating gas flows from one side (right side in the figure) to the other side (left side in the figure) in the direction of extension of the heating gas pipe 5 (left-right direction in the figure). RD2 in Figure 4 indicates the flow direction of the heating gas flowing through the heating gas pipe 5.

[0041] In some embodiments, as shown in Figures 7 and 8, each of the plurality of heating gas pipes 5 described above includes at least one (or more in the illustrated example) first heating gas pipe 5A through which the heating gas flows from one side (right side in the figure) to the other side (left side in the figure) in the extending direction (left-right direction in the figure) of the heating gas pipe 5, and at least one (or more in the illustrated example) second heating gas pipe 5B through which the heating gas flows from the other side (left side in the figure) to the one side (right side in the figure) in the extending direction of the heating gas pipe 5. RD2 in Figures 7 and 8 indicates the flow direction of the heating gas flowing through the first heating gas pipe 5A, and RD3 in Figures 7 and 8 indicates the flow direction of the heating gas flowing through the second heating gas pipe 5B.

[0042] In the embodiment shown in Figure 7, the heating gas flow direction of each stage heating gas piping 5(5A) is opposite to that of adjacent heating gas piping 5(5B) in the first direction. In the embodiment shown in Figure 8, the heating gas flow direction of each stage heating gas piping 5(5A) is opposite to that of adjacent heating gas piping 5(5B) in the same stage. In other embodiments, the heating gas flow direction of multiple heating gas pipings 5 ​​constituting one stage may be the same, while the heating gas flow direction of multiple heating gas pipings 5 ​​constituting other stages adjacent to the above stage may be opposite to that of the multiple heating gas pipings 5 ​​constituting the above stage.

[0043] According to the above configuration, by setting the flow direction of the exhaust gas flowing through the at least one first heating gas pipe 5A and the exhaust gas flowing through the at least one second heating gas pipe 5B to opposite directions, it is possible to suppress uneven heat transfer from the heating gas flowing through the multiple heating gas pipes 5A and 5B to the oxidation catalyst device 3 in the direction of extension of the heating gas pipes 5. As a result, the entire oxidation catalyst device 3 can be heated uniformly, and the catalyst heating time required for the oxidation catalyst to perform at the start of use of the oxidation catalyst device 3 can be shortened.

[0044] (Inlet gas duct, outlet gas duct) Each of the above-mentioned multiple heating gas pipes 5 (5A, 5B) has a heating gas inlet formed at one end in the direction of extension of the heating gas pipe 5 for introducing heating gas from the outside into the heating gas pipe 5. Each of the above-mentioned multiple heating gas pipes 5 (5A, 5B) has a heating gas outlet formed at the other end in the direction of extension of the heating gas pipe 5 for discharging heating gas from the heating gas pipe 5 to the outside.

[0045] In some embodiments, the oxidation catalyst heating system 2 described above further comprises an inlet gas duct 21 attached to the catalyst casing 4 and an outlet gas duct 22 attached to the catalyst casing 4. Each of the multiple heating gas pipes 5 has a heating gas inlet connected to a common inlet gas duct 21 and a heating gas outlet connected to a common outlet gas duct 22.

[0046] As shown in Figures 4 and 6, the inlet gas duct 21 has an internal space 210 through which the heated gas flows before being introduced into the heated gas piping 5, between it and the catalyst casing 4. The inlet gas duct 21 has an inlet 211 for introducing heated gas into the interior (internal space 210) of the inlet gas duct 21, and multiple communication holes 212 that connect the internal space 210 of the inlet gas duct 21 to the heated gas inlets of the multiple heated gas piping 5, respectively.

[0047] As shown in Figure 4, the outlet gas duct 22 has an internal space 220 through which the heated gas that has passed through the heated gas piping 5 flows, between it and the catalyst casing 4. The outlet gas duct 22 has an outlet 221 for discharging the heated gas from the inside of the outlet gas duct 22 (internal space 220), and multiple communication holes 222 that connect the internal space 220 of the outlet gas duct 22 to the heated gas outlets of the multiple heated gas piping 5, respectively.

[0048] In the embodiment shown in Figure 4, the inlet gas duct 21 is attached to one end of the catalyst casing 4 (the end on one side (right side in the figure) in the extending direction (left-right direction in the figure) of the heating gas piping 5). The outlet gas duct 22 is attached to the other end of the catalyst casing 4 (the end on the other side (left side in the figure) in the extending direction (left-right direction in the figure) of the heating gas piping 5).

[0049] In the embodiments shown in Figures 7 and 8, the inlet gas duct 21 includes a first inlet gas duct 21A through which an internal space 210A is formed for the heated gas before it is introduced into the first heated gas piping 5A, and a second inlet gas duct 21B through which an internal space 210B is formed for the heated gas before it is introduced into the second heated gas piping 5B. The outlet gas duct 22 includes a first outlet gas duct 22A through which an internal space 220A is formed for the heated gas that has passed through the first heated gas piping 5A, and a second outlet gas duct 22B through which an internal space 220B is formed for the heated gas that has passed through the second heated gas piping 5B.

[0050] Each of the multiple first heating gas pipes 5A has its heating gas inlet connected to a common first inlet gas duct 21A and its heating gas outlet connected to a common first outlet gas duct 22A. Each of the multiple second heating gas pipes 5B has its heating gas inlet connected to a common second inlet gas duct 21B and its heating gas outlet connected to a common second outlet gas duct 22B.

[0051] In the embodiments shown in Figures 7 and 8, the first inlet gas duct 21A and the second outlet gas duct 22B are located on one side (right side in the figures) of the heating gas piping 5 in the direction of extension of the heating gas piping 5. In the illustrated example, the second outlet gas duct 22B is located on one side of the first inlet gas duct 21A, but it may also be located on the other side (left side in the figures) of the first inlet gas duct 21A.

[0052] In the embodiments shown in Figures 7 and 8, the first inlet gas duct 21A and the second outlet gas duct 22B are formed by a first gas duct body 44 that forms an internal space including an internal space 210A and an internal space 220B, and a partition wall 45 that divides the internal space of the first gas duct body 44 into internal space 210A and internal space 220B. In the illustrated example, the partition wall 45 extends along a direction that intersects (orthogonal in the illustrated example) the extending direction of the heating gas piping 5.

[0053] In the embodiments shown in Figures 7 and 8, the second inlet gas duct 21B and the first outlet gas duct 22A are located on the other side (left side in the figures) of the heating gas piping 5 in the direction of extension of the heating gas piping 5. In the illustrated example, the first outlet gas duct 22A is located on the other side of the second inlet gas duct 21B, but it may also be located on one side (right side in the figures) of the second inlet gas duct 21B.

[0054] In the embodiments shown in Figures 7 and 8, the second inlet gas duct 21B and the first outlet gas duct 22A are formed by a second gas duct body 46 that forms an internal space including an internal space 210B and an internal space 220A, and a partition wall 47 that divides the internal space of the second gas duct body 46 into internal space 210B and internal space 220A. In the illustrated example, the partition wall 47 extends along a direction that intersects (orthogonal in the illustrated example) the extending direction of the heating gas piping 5.

[0055] As shown in Figure 7, the inlet gas ducts 21A and 21B are formed with inlet ports 211A and 211B for introducing heating gas into the interior (internal spaces 210A and 210B) of the inlet gas ducts 21A and 21B, and multiple communication holes 212A and 212B that connect the internal spaces 210A and 210B of the inlet gas ducts 21A and 21B to the heating gas inlet ports of the multiple heating gas pipes 5, respectively.

[0056] As shown in Figure 7, the outlet gas ducts 22A and 22B are formed with outlets 221A and 221B for discharging heated gas from inside the outlet gas ducts 22A and 22B (internal spaces 220A and 220B), and multiple communication holes 222A and 222B that connect the internal spaces 220A and 220B of the outlet gas ducts 22A and 22B to the heated gas outlets of the multiple heated gas pipes 5, respectively.

[0057] In the illustrated example, the first gas duct body 44 has the inlet 211A, outlet 221B, and multiple communication holes 212A as shown in Figure 7. The first gas duct body 44 has multiple insertion holes 441 through which the second heating gas pipes 5B are inserted. The partition wall 45 has the multiple communication holes 222B as described above.

[0058] In the illustrated example, the second gas duct body 46 has the inlet 211B, outlet 221A, and multiple communication holes 212B as shown in Figure 7. The second gas duct body 46 has multiple insertion holes 461 through which the first heating gas pipe 5A is inserted. The partition wall 47 has the multiple communication holes 222A as described above. The inlet 211A, 211B and outlet 221A, 221B are open upward in the vertical direction.

[0059] According to the above configuration, by connecting multiple heating gas pipes 5 to a common inlet gas duct 21, the differences in temperature and flow rate of the exhaust gas introduced from the inlet gas duct 21 to the multiple heating gas pipes 5 can be minimized. Furthermore, by connecting multiple heating gas pipes 5 to a common outlet gas duct 22, the differences in temperature and flow rate of the exhaust gas discharged from the multiple heating gas pipes 5 to the outlet gas duct 22 can be minimized. By minimizing the differences in temperature and flow rate of the exhaust gas introduced to the multiple heating gas pipes 5, thermal energy is uniformly transferred from the heating gas flowing through the multiple heating gas pipes 5 to the oxidation catalyst device 3. This allows the entire oxidation catalyst device 3 to be heated uniformly, and the catalyst heating time required for the oxidation catalyst to perform at the start of use of the oxidation catalyst device 3 can be shortened.

[0060] (Orifice) In some embodiments, the multiple heating gas pipes 5 connected to the common inlet gas duct 21, as shown in Figure 7, include a nearby heating gas pipe 5C connected to the inlet gas duct 21 at a relatively close distance from the inlet 211 of the inlet gas duct 21, and a far-side heating gas pipe 5D connected to the inlet gas duct 21 at a distance further from the inlet 211 than the nearby heating gas pipe 5C. The nearby heating gas pipe 5C has a shorter distance from the inlet 211 to the heating gas inlet compared to the far-side heating gas pipe 5D. In the embodiment shown in Figure 7, the far-side heating gas pipe 5D is located further from the inlet 211 of the inlet gas duct 21 in the vertical direction than the nearby heating gas pipe 5C. In the embodiment shown in Figure 4, the far-side heating gas pipe 5D is located further from the inlet 211 of the inlet gas duct 21 in the horizontal direction than the nearby heating gas pipe 5C.

[0061] In some embodiments, as shown in Figure 7, an orifice 81 is provided in either the nearby heating gas piping 5C, the connection point C1 between the nearby heating gas piping 5C and the inlet gas duct 21, or the connection point C2 between the nearby heating gas piping 5C and the outlet gas duct 22, with an opening area 50C smaller than the opening area 50D of the far-side heating gas piping 5D. Here, the opening area 50C of the nearby heating gas piping 5C refers to the minimum area of ​​the flow path for the heating gas flowing through the nearby heating gas piping 5C between the communication hole 212 of the inlet gas duct 21 and the communication hole 222 of the outlet gas duct 22. The opening area 50D of the far-side heating gas piping 5D refers to the minimum area of ​​the flow path for the heating gas flowing through the far-side heating gas piping 5D between the communication hole 212 of the inlet gas duct 21 and the communication hole 222 of the outlet gas duct 22.

[0062] In the embodiment shown in Figure 7, as shown in Figure 7, the flow path cross-sectional area of ​​the nearby heating gas pipe 5C is the same as the flow path cross-sectional area of ​​the far-side heating gas pipe 5D (within a range of ±5% of the flow path cross-sectional area of ​​the nearby heating gas pipe 5C). By providing an orifice (restriction) 81 smaller than the flow path cross-sectional areas of the nearby heating gas pipe 5C and the far-side heating gas pipe 5D at the connection point C1 between the nearby heating gas pipe 5C and the inlet gas duct 21, the opening area 50C of the nearby heating gas pipe 5C is smaller than the opening area 50D of the far-side heating gas pipe 5D.

[0063] In the embodiment shown in Figure 7, the orifice 81 consists of an opening formed in the orifice plate 8. The orifice plate 8 is positioned at the connection point C1 between the inlet gas duct 21 and the nearby heating gas piping 5C such that the orifice 81, which is its opening, closes off a portion of the communication hole 212 of the inlet gas duct 21. In the embodiment shown in Figure 7, the orifice plate 8 is positioned in the internal space 210A formed inside the inlet gas duct 21 and is fixed to the inlet gas duct 21 by welding or the like. When viewed from the extending direction of the nearby heating gas piping 5C, the opening area of ​​the orifice 81 is smaller than the flow path cross-sectional area of ​​the nearby heating gas piping 5C.

[0064] With the above configuration, the orifice 81 increases the pressure loss in the nearby heating gas piping 5C, making it easier to introduce exhaust gas from the inlet gas duct 21 to the distant heating gas piping 5D. By minimizing the difference between the flow rate of exhaust gas flowing through the nearby heating gas piping 5C and the flow rate of exhaust gas flowing through the distant heating gas piping 5D, thermal energy is uniformly transferred from the nearby heating gas piping 5C and the distant heating gas piping 5D to the oxidation catalyst device 3. As a result, the entire oxidation catalyst device 3 can be heated uniformly, and the catalyst heating time required for the oxidation catalyst to perform at its full potential at the start of use of the oxidation catalyst device 3 can be shortened.

[0065] The installation configuration of the orifice 81 is not limited to the embodiment shown in Figure 7. For example, the orifice plate 8 may be fixed inside the nearby heating gas piping 5C. The orifice plate 8 may be positioned in an internal space 220A formed inside the outlet gas duct 22 such that its opening, the orifice 81, closes a portion of the communication hole 222 of the outlet gas duct 22, and may be fixed to the outlet gas duct 22 by welding or the like. The orifice plate 8 may be positioned between either the inlet gas duct 21 or the outlet gas duct 22 and the nearby heating gas piping 5C, and may be fixed to them by welding or the like.

[0066] Furthermore, an orifice may be provided in at least a portion of the nearby heating gas piping 5C to make the flow path cross-sectional area smaller than that of the distant heating gas piping 5D. The flow path cross-sectional area of ​​the nearby heating gas piping 5C may be made smaller than that of the distant heating gas piping 5D. Also, the communication hole 212 to which the nearby heating gas piping 5C is connected may be made smaller than the communication hole 212 to which the distant heating gas piping 5D is connected, and the communication hole 222 to which the nearby heating gas piping 5C is connected may be made smaller than the communication hole 222 to which the distant heating gas piping 5D is connected. Furthermore, this disclosure is also applicable to the embodiment shown in Figure 4. That is, in the embodiment shown in Figure 4, an orifice may be provided to make the opening area of ​​the heating gas piping 5 with a shorter distance from the inlet 211 to the heating gas inlet smaller than the opening area of ​​the heating gas piping 5 with a longer distance from the inlet 211 to the heating gas inlet than that of the heating gas piping 5.

[0067] (First method for raising the temperature of the oxidation catalyst apparatus) A method for raising the temperature of an oxidation catalyst device according to several embodiments is a method for raising the temperature of an oxidation catalyst device 3 configured to oxidize exhaust gas discharged from the internal combustion engine 11 of the internal combustion engine system 1 described above. The oxidation catalyst device 3 described above includes a plurality of oxidation catalyst elements 31, each containing a methane oxidation catalyst configured to oxidize methane contained in the exhaust gas. The internal combustion engine 11 includes a dual-fuel engine that can operate by switching between a first fuel FU1 containing methane in the exhaust gas components and a second fuel FU2 not containing methane in the exhaust gas components, as shown in Figure 1. Examples of the first fuel FU1 include liquefied natural gas. Examples of the second fuel FU2 include fuel oil such as diesel fuel or marine gas oil.

[0068] In some embodiments, the above-described method for heating an oxidation catalyst includes a first operating step of introducing a first exhaust gas discharged from an internal combustion engine 11 into a catalyst casing 4 housing an oxidation catalyst device 3 while the internal combustion engine 11 is operating with a first fuel FU1, and a second operating step of introducing the first exhaust gas discharged from the internal combustion engine 11 into at least one heating gas piping 5 located inside the catalyst casing 4 and positioned between a pair of adjacent oxidation catalyst elements 31 among a plurality of oxidation catalyst elements 31, while the internal combustion engine 11 is operating with a second fuel FU2.

[0069] In Figure 1, the solid arrows indicate the flow of the first exhaust gas during the first operating step, and the dotted arrows indicate the flow of the first exhaust gas during the second operating step.

[0070] According to the above method, in the first operating step, while the internal combustion engine 11 is operating using the first fuel FU1, the exhaust gas discharged from the internal combustion engine 11 is introduced into the catalyst casing 4, thereby allowing the methane contained in the exhaust gas to be oxidized by the methane oxidation catalyst. In the second operating step, while the internal combustion engine 11 is operating using the second fuel FU2, exhaust gas that does not contain methane can be introduced into the at least one heating gas piping 5 discharged from the internal combustion engine 11. In this case, since exhaust gas discharged from the internal combustion engine 11 that does not require oxidation by the oxidation catalyst 3 can be used as the heating gas to heat the oxidation catalyst 3, it is not necessary to separately provide a heater or other device to keep the oxidation catalyst 3 warm. This makes it possible to suppress the enlargement and complexity of the equipment for heating the oxidation catalyst 3 and the structure of the internal combustion engine system 1 equipped with such equipment, and reduces the space occupied by the equipment and the internal combustion engine system 1. This embodiment can reduce the space occupied by the equipment for raising the temperature of the oxidation catalyst device 3 and the internal combustion engine system 1, making it suitable for use in ships and other vessels where space is limited.

[0071] Furthermore, according to the above method, at least one heating gas pipe 5 is positioned between a pair of oxidation catalyst elements 31 that are adjacent to each other inside the catalyst casing 4. This allows the thermal energy of the heating gas flowing through the heating gas pipe 5 to be efficiently transferred to each of the pair of oxidation catalyst elements 31 flanking the heating gas pipe 5. As a result, the entire oxidation catalyst device 3 can be effectively heated, and the catalyst heating time required for the oxidation catalyst to perform at full capacity at the start of use of the oxidation catalyst device 3 can be shortened.

[0072] (Exhaust gas branching line, exhaust gas return line) In some embodiments of the oxidation catalyst heating system 2, as shown in Figure 1, the system further includes an exhaust gas branch line 23 that branches off from the exhaust gas line 12 upstream of the catalyst casing 4. Each of the plurality of heating gas pipes 5 described above is configured to receive exhaust gas through the exhaust gas branch line 23.

[0073] In the embodiment shown in Figure 1, the oxidation catalyst heating system 2 includes the exhaust gas branch line 23 described above, and an exhaust gas return line 24 for returning exhaust gas from each of the plurality of heating gas pipes 5 described above to the downstream side of the catalyst casing 4 of the exhaust gas line 12. The upstream end of the exhaust gas branch line 23 is connected to the branch section P1 of the first upstream exhaust gas line 12A, and the downstream end is connected to the inlet 211 of the inlet gas duct 21. The upstream end of the exhaust gas return line 24 is connected to the outlet 221 of the outlet gas duct, and the downstream end is connected to the confluence section P2 of the first downstream exhaust gas line 12B. The first exhaust gas, which has been guided to the plurality of heating gas pipes 5 via the exhaust gas branch line 23, is guided to the downstream side of the catalyst casing 4 of the exhaust gas line 12 via the exhaust gas return line 24.

[0074] According to the above configuration, the relatively high-temperature first exhaust gas discharged from the internal combustion engine 11 can be used as the heating gas. In this case, the size and complexity of the oxidation catalyst heating system 2 and the internal combustion engine system 1 equipped with the oxidation catalyst heating system 2 can be suppressed, and the space occupied by the oxidation catalyst heating system 2 and the internal combustion engine system 1 can be reduced.

[0075] (First exhaust gas path switching device) One internal combustion engine system 1 according to several embodiments, as shown in Figure 1, comprises an oxidation catalyst heating system 2 comprising the oxidation catalyst device 3, catalyst casing 4, and at least one heating gas pipe 5 described above, and a first exhaust gas path switching device 7 configured to switch the path of the exhaust gas discharged from the internal combustion engine 11 described above. The oxidation catalyst device 3 described above includes a methane oxidation catalyst configured to oxidize methane contained in the exhaust gas. The internal combustion engine 11 described above includes a dual-fuel engine capable of operating by switching between a first fuel FU1 containing methane in the exhaust gas components and a second fuel FU2 not containing methane in the exhaust gas components.

[0076] The first exhaust gas path switching device 7 is configured to guide the first exhaust gas discharged from the internal combustion engine 11 to the catalyst casing 4 when the internal combustion engine 11 is operating using the first fuel FU1, and to guide the first exhaust gas discharged from the internal combustion engine 11 to at least one of the above-mentioned temperature-boosting gas pipes 5 when the internal combustion engine 11 is operating using the second fuel FU2.

[0077] In the embodiment shown in Figure 1, the first exhaust gas path switching device 7 includes a first on-off valve 71 provided downstream of the branching point P1 of the first upstream exhaust gas line 12A, and a second on-off valve 72 provided in the exhaust gas branching line 23.

[0078] When the internal combustion engine 11 is operating using the first fuel FU1, the first on-off valve 71 is open and the second on-off valve 72 is closed. When the internal combustion engine 11 is operating using the second fuel FU2, the second on-off valve 72 is open and the first on-off valve 71 is closed. As shown in Figure 1, the first exhaust gas path switching device 7 may further include a control device (controller) 70 that controls the opening and closing of the first on-off valve 71 and the second on-off valve 72. In the oxidation catalyst heating method described above, the opening and closing of the first on-off valve 71 and the second on-off valve 72 may be changed manually.

[0079] According to the above configuration, the first exhaust gas path switching device 7 allows exhaust gas discharged from the internal combustion engine 11 to be introduced into the catalyst casing 4 while the internal combustion engine 11 is operating using the first fuel FU1, thereby oxidizing the methane contained in the exhaust gas by the methane oxidation catalyst. The first exhaust gas path switching device 7 also allows exhaust gas that does not contain methane to be introduced into the at least one heating gas piping 5 while the internal combustion engine 11 is operating using the second fuel FU2. In this case, exhaust gas discharged from the internal combustion engine 11 that does not require oxidation by the oxidation catalyst 3 can be used as the heating gas to heat the oxidation catalyst 3, thus suppressing the enlargement and complexity of the oxidation catalyst heating system 2 and the internal combustion engine system 1 equipped with the oxidation catalyst heating system 2, and reducing the space occupied by the oxidation catalyst heating system 2 and the internal combustion engine system 1.

[0080] (Second method for raising the temperature of the oxidation catalyst apparatus) A method for raising the temperature of an oxidation catalyst device according to several embodiments is a method for raising the temperature of an oxidation catalyst device 3 configured to oxidize exhaust gas discharged from the internal combustion engine 11 of the internal combustion engine system 1 described above. The oxidation catalyst device 3 described above includes a plurality of oxidation catalyst elements 31, each containing a methane oxidation catalyst configured to oxidize methane contained in the exhaust gas.

[0081] In some embodiments, the above-described method for heating the oxidation catalyst device includes an exhaust gas introduction step in which, while the internal combustion engine 11 is stopped, a second exhaust gas, which does not contain methane in the exhaust gas components discharged from another internal combustion engine 13 different from the internal combustion engine 11, is introduced into at least one heating gas piping 5 located inside the catalyst casing 4 housing the oxidation catalyst device 3 and positioned between a pair of adjacent oxidation catalyst elements 31 among a plurality of oxidation catalyst elements 31.

[0082] In the embodiment shown in Figure 2, the internal combustion engines 11 and 13 include dual-fuel engines capable of switching between a first fuel FU1 containing methane in its exhaust gas components and a second fuel FU2 not containing methane in its exhaust gas components, as shown in Figure 2. The solid arrows in Figure 2 indicate the flow of the first and second exhaust gases when the internal combustion engines 11 and 13 are operating with the first fuel FU1, and the dotted arrows in Figure 2 indicate the flow of the second exhaust gas when the internal combustion engine 11 is stopped and the internal combustion engine 13 is operating with the second fuel FU2.

[0083] According to the above method, the exhaust gas introduction step allows for the introduction of a second exhaust gas, which does not contain methane, from another internal combustion engine 13 while the internal combustion engine 11 is stopped, into the at least one heating gas piping 5. In this case, exhaust gas that does not require oxidation by the oxidation catalyst 3, emitted from another internal combustion engine 13, can be used as the heating gas to heat the oxidation catalyst 3. This reduces the size and complexity of the equipment for heating the oxidation catalyst 3 and the internal combustion engine system 1 equipped with such equipment, thereby reducing the space occupied by the equipment and the internal combustion engine system 1. This embodiment can reduce the space occupied by the equipment for heating the oxidation catalyst 3 and the internal combustion engine system 1, making it suitable for use in ships and other vessels where space is limited. Furthermore, according to the above method, exhaust gas can be introduced into the at least one heating gas piping 5 even while the internal combustion engine 11 is stopped, and the oxidation catalyst 3 can be heated by the exhaust gas flowing through the heating gas piping 5.

[0084] Furthermore, according to the above method, at least one heating gas pipe 5 is positioned between a pair of oxidation catalyst elements 31 that are adjacent to each other inside the catalyst casing 4. This allows the thermal energy of the heating gas flowing through the heating gas pipe 5 to be efficiently transferred to each of the pair of oxidation catalyst elements 31 flanking the heating gas pipe 5. As a result, the entire oxidation catalyst device 3 can be effectively heated, and the catalyst heating time required for the oxidation catalyst to perform at full capacity at the start of use of the oxidation catalyst device 3 can be shortened.

[0085] In some embodiments of the oxidation catalyst heating system 2, as shown in Figure 2, the system further comprises other exhaust gas lines 14A, 27, distinct from the exhaust gas line 12, through which the second exhaust gas discharged from the second internal combustion engine 13 described above flows. Each of the plurality of heating gas pipes 5 described above is configured to receive exhaust gas via the other exhaust gas lines 14A, 27 described above.

[0086] In the embodiment shown in Figure 2, the oxidation catalyst heating system 2 further comprises an oxidation catalyst device 3A, a catalyst casing 4A, a plurality of heating gas pipes 5E, an inlet gas duct 21C attached to the catalyst casing 4A, and an outlet gas duct 22C attached to the catalyst casing 4A. The oxidation catalyst device 3A, catalyst casing 4A, heating gas pipes 5E, inlet gas duct 21C, and outlet gas duct 22C may have the same structure as the oxidation catalyst device 3, catalyst casing 4, heating gas pipes 5, inlet gas duct 21, and outlet gas duct 22 described above. The catalyst casing 4A is provided in the second exhaust gas line 14 and is configured to house the oxidation catalyst device 3A and the plurality of heating gas pipes 5E.

[0087] The second exhaust gas line 14 includes a second upstream exhaust gas line 14A for guiding the second exhaust gas from the internal combustion engine 13 to the catalyst casing 4A, and a second downstream exhaust gas line 14B for guiding the second exhaust gas downstream in the flow direction of the second exhaust gas from the catalyst casing 4A.

[0088] In the embodiment shown in Figure 2, the oxidation catalyst heating system 2 includes a first exhaust gas branch line 25 that branches off from upstream of the catalyst casing 4A of the second exhaust gas line 14 and guides the second exhaust gas to a plurality of heating gas pipes 5E, and a first exhaust gas return line 26 that returns the exhaust gas from each of the plurality of heating gas pipes 5E to the downstream side of the catalyst casing 4A of the exhaust gas line 14. The upstream end of the first exhaust gas branch line 25 is connected to the branch P3 of the second upstream exhaust gas line 14A, and the downstream end is connected to the inlet gas duct 21C. The upstream end of the first exhaust gas return line 26 is connected to the outlet gas duct 22C, and the downstream end is connected to the junction P4 of the second downstream exhaust gas line 14B. The second exhaust gas guided to the plurality of heating gas pipes 5E via the first exhaust gas branch line 25 is guided downstream of the catalyst casing 4A of the exhaust gas line 14 via the first exhaust gas return line 26.

[0089] In the embodiment shown in Figure 2, the oxidation catalyst heating system 2 includes a second exhaust gas branch line 27 that branches off from the first exhaust gas branch line 25 and guides the second exhaust gas to a plurality of heating gas pipes 5, and a second exhaust gas return line 28 that returns the exhaust gas from each of the plurality of heating gas pipes 5E to a side downstream of the catalyst casing 4A of the exhaust gas line 14. The upstream end of the second exhaust gas branch line 27 is connected to the branching section P5 of the first exhaust gas branch line 25, and the downstream end is connected to the inlet gas duct 21. The upstream end of the second exhaust gas return line 28 is connected to the outlet gas duct 22, and the downstream end is connected to the junction section P6 of the second downstream exhaust gas line 14B. The second exhaust gas guided to the plurality of heating gas pipes 5 via the second exhaust gas branch line 27 is guided downstream of the catalyst casing 4A of the exhaust gas line 14 via the second exhaust gas return line 28.

[0090] According to the above configuration, the relatively high-temperature second exhaust gas discharged from the second internal combustion engine 13 can be used as the heating gas. In this case, the size and complexity of the oxidation catalyst heating system 2 and the internal combustion engine system 1 equipped with the oxidation catalyst heating system 2 can be suppressed, and the space occupied by the oxidation catalyst heating system 2 and the internal combustion engine system 1 can be reduced. Furthermore, according to the above configuration, even when the internal combustion engine 11 is stopped, the second exhaust gas can be introduced into the at least one heating gas piping 5, and the oxidation catalyst device 3 can be heated by the second exhaust gas flowing through the heating gas piping 5.

[0091] In some embodiments of the oxidation catalyst heating system 2, instead of the second exhaust gas branch line 27 described above, a second exhaust gas branch line may be provided, whose upstream end is connected upstream of the confluence P4 and confluence P6 of the second downstream exhaust gas line 14B, and whose downstream end is connected to the inlet gas duct 21. With the above configuration, exhaust gas containing methane in the exhaust gas components discharged from the second internal combustion engine 13 can be oxidized by the oxidation catalyst device 3 and then introduced into the above at least one heating gas piping 5. In this case, when the internal combustion engine 11 is stopped, the exhaust gas from the other internal combustion engine (second internal combustion engine 13) after oxidation treatment can be used as a warming gas. Furthermore, regardless of whether the fuel used to operate the second internal combustion engine 13 is a first fuel containing methane in the exhaust gas components or a second fuel not containing methane in the exhaust gas components, the exhaust gas from the second internal combustion engine 13 after oxidation treatment can be used as a warming gas.

[0092] One internal combustion engine system 1 according to several embodiments, as shown in Figure 2, comprises an oxidation catalyst heating system 2 comprising the oxidation catalyst devices 3, 3A, catalyst casings 4, 4A and heating gas piping 5, 5E described above, and a second exhaust gas path switching device 7A configured to switch the path of the second exhaust gas discharged from the internal combustion engine 13 described above. The oxidation catalyst device 3 described above includes a methane oxidation catalyst configured to oxidize methane contained in the exhaust gas. The internal combustion engine 13 described above includes a dual-fuel engine capable of operating by switching between a first fuel FU1 containing methane in the exhaust gas components and a second fuel FU2 not containing methane in the exhaust gas components.

[0093] The second exhaust gas path switching device 7A is configured to guide the second exhaust gas to the catalyst casing 4A when the internal combustion engine 13 is operating with the first fuel FU1, and to guide the second exhaust gas to the heating gas pipes 5 and 5E when the internal combustion engine 11 is stopped and the internal combustion engine 13 is operating with the second fuel FU2.

[0094] In the embodiment shown in Figure 2, the second exhaust gas path switching device 7A includes a first on-off valve 71A provided downstream of the branching point P3 of the second upstream exhaust gas line 14A, and a second on-off valve 72A provided upstream of the branching point P5 of the first exhaust gas branch line 25.

[0095] When the internal combustion engine 13 is operating using the first fuel FU1, the first on-off valve 71A is open and the second on-off valve 72A is closed. When the internal combustion engine 11 is stopped and the internal combustion engine 13 is operating using the second fuel FU2, the second on-off valve 72A is open and the first on-off valve 71A is closed. As shown in Figure 2, the second exhaust gas path switching device 7A may further include a control device (controller) 70A that controls the opening and closing of the first on-off valve 71A and the second on-off valve 72A. In the oxidation catalyst heating method described above, the opening and closing of the first on-off valve 71A and the second on-off valve 72A may be changed manually.

[0096] According to the above configuration, the second exhaust gas path switching device 7A allows exhaust gas that does not contain methane in its exhaust gas components, emitted from the other internal combustion engine 13, to be introduced into the above-mentioned heating gas piping 5 while the other internal combustion engine 13 is operating using the second fuel FU2. In this case, exhaust gas that does not require oxidation by the oxidation catalyst device 3, emitted from the other internal combustion engine 13, can be used as the heating gas to heat the oxidation catalyst device 3. This suppresses the increase in size and complexity of the oxidation catalyst heating system 2 and the internal combustion engine system 1 equipped with the oxidation catalyst heating system 2, and reduces the space occupied by the oxidation catalyst heating system 2 and the internal combustion engine system 1.

[0097] In this specification, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" shall not only describe such arrangements strictly, but also describe states of relative displacement with tolerances or angles or distances that allow for the same function to be achieved. For example, expressions such as "identical," "equal," and "homogeneous" that describe things being in an equal state not only describe a state of being strictly equal, but also describe a state in which there is a tolerance or a difference that is sufficient to achieve the same function. Furthermore, in this specification, expressions describing shapes such as quadrilaterals and cylindrical shapes shall not only represent geometrically precise quadrilaterals and cylindrical shapes, but also shapes that include uneven surfaces, chamfered surfaces, etc., to the extent that the same effect can be achieved. Furthermore, in this specification, the expressions “equipment,” “includes,” or “possess” of a component are not exclusive expressions that exclude the existence of other components.

[0098] This disclosure is not limited to the embodiments described above, but also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0099] The contents described in some of the embodiments above can be understood, for example, as follows:

[0100] 1) The oxidation catalyst heating system (2) according to at least one embodiment of the present disclosure is An exhaust gas line (12) through which exhaust gas emitted from an internal combustion engine (11) flows, A catalyst casing (4) houses an oxidation catalyst device (3) which is provided in the exhaust gas line (12) and includes a plurality of oxidation catalyst elements (31) configured to oxidize the exhaust gas, The device comprises at least one heating gas pipe (5) through which a heating gas for heating the oxidation catalyst device (3) flows, the heating gas pipe (5) being located inside the catalyst casing (4) and positioned between a pair of adjacent oxidation catalyst elements (31) among the plurality of oxidation catalyst elements (31).

[0101] According to the configuration described in 1) above, the oxidation catalyst device (3) can be heated by the heating gas flowing through the at least one heating gas pipe (5) while the oxidation catalyst device (3) is out of use. Since the at least one heating gas pipe (5) is positioned between a pair of oxidation catalyst elements (31) that are adjacent to each other inside the catalyst casing (4), the thermal energy of the heating gas flowing through the heating gas pipe (5) can be efficiently transferred to each of the pair of oxidation catalyst elements (31) flanking the heating gas pipe (5). This effectively heats up the entire oxidation catalyst device (3), and shortens the catalyst heating time required for the oxidation catalyst to perform at the start of use of the oxidation catalyst device (3).

[0102] 2) In some embodiments, the oxidation catalyst heating system (2) described in 1) above, The at least one heating gas pipe (5) extends along a direction intersecting the flow direction (first direction RD1) of the exhaust gas flowing inside the catalyst casing (4).

[0103] According to the configuration described in 2) above, the at least one heating gas pipe (5) extends along a direction intersecting the flow direction of the exhaust gas (first direction RD1) flowing inside the catalyst casing (4), so that the thermal energy of the heating gas flowing through the heating gas pipe (5) can be efficiently transferred to the entire oxidation catalyst device (3) located inside the catalyst casing (4). This allows the oxidation catalyst device (3) to be effectively heated.

[0104] 3) In some embodiments, the oxidation catalyst heating system (2) described in 2) above, The aforementioned at least one heating gas pipe (5) is It has a rectangular cross-sectional shape with a pair of long sides and a pair of short sides, Each of the pair of long sides (51, 52) of the heating gas pipe (5) having the long side is in contact with the pair of oxidation catalyst elements (31).

[0105] According to the configuration described in 3) above, each of the pair of relatively large long sides (51, 52) of the at least one heating gas pipe (5) is in contact with the oxidation catalyst element (31). The thermal energy of the heating gas flowing through the heating gas pipe (5) can be directly and efficiently transferred to each of the oxidation catalyst elements (31) facing the pair of long sides (51, 52) via the pair of long sides (51, 52) with a large heat transfer area. This allows the oxidation catalyst device (3) to be heated effectively.

[0106] 4) In some embodiments, the oxidation catalyst heating system (2) described in 3) above, The aforementioned at least one heating gas pipe (5) is When viewed from a first direction (RD1), which is the flow direction of the exhaust gas flowing inside the catalyst casing (4), the catalyst casing (4) includes a plurality of heating gas pipes (5) that are spaced apart in a direction intersecting the extending direction of the heating gas pipes (5), When viewed from the first direction (RD1), the oxidation catalyst heating system (2) is as follows: A plurality of partition plates (6) are provided, each having one end connected to one of a pair of adjacent heating gas pipes (5) arranged in a direction intersecting the extending direction of the heating gas pipe (5), and the other end connected to the other heating gas pipe, further comprising a plurality of partition plates (6) arranged at intervals in the extending direction of the heating gas pipe (5), Each of the plurality of oxidation catalyst elements (31) is housed in a space partitioned by the pair of heating gas pipes (5) and the plurality of partition plates (6).

[0107] According to the configuration in 4) above, an oxidation catalyst element (31) can be housed in each of the spaces partitioned by the pair of heating gas pipes (5) and the multiple partition plates (6), making it easy to position the oxidation catalyst element (31). Furthermore, the oxidation catalyst element (31) housed in the space receives thermal energy from the heating gas flowing through the pair of heating gas pipes (5) via the pair of heating gas pipes (5) and the multiple partition plates (6) surrounding the oxidation catalyst element (31). This allows the entire oxidation catalyst element (31) housed in the space to be effectively heated.

[0108] 5) In some embodiments, the oxidation catalyst heating system (2) described in any of 1) to 3) above, The exhaust gas branch line (23) further branches off from the upstream side of the catalyst casing (4) of the exhaust gas line (12), The at least one heating gas piping (5) is configured to receive the exhaust gas via the exhaust gas branch line (23).

[0109] According to the configuration in 5) above, the relatively high-temperature exhaust gas discharged from the internal combustion engine (11) can be used as the heating gas. In this case, the size and complexity of the oxidation catalyst heating system (2) and the internal combustion engine system (1) equipped with the oxidation catalyst heating system (2) can be suppressed, and the space occupied by the oxidation catalyst heating system (2) and the internal combustion engine system (1) can be reduced.

[0110] 6) In some embodiments, the oxidation catalyst heating system (2) described in any of 1) to 3) above, The system further includes other exhaust gas lines (14A, 27) different from the exhaust gas line (12), through which exhaust gas discharged from another internal combustion engine (13) different from the internal combustion engine (11) flows. The at least one heating gas piping (5) is configured to receive the exhaust gas via the other exhaust gas lines (14A, 27).

[0111] According to the configuration in 6) above, relatively high-temperature exhaust gas discharged from another internal combustion engine (13) can be used as the heating gas. In this case, the size and complexity of the oxidation catalyst heating system (2) and the internal combustion engine system (1) equipped with the oxidation catalyst heating system (2) can be suppressed, and the space occupied by the oxidation catalyst heating system (2) and the internal combustion engine system (1) can be reduced. Furthermore, according to the configuration in 6) above, even when the internal combustion engine (11) is stopped, exhaust gas can be introduced into the at least one heating gas piping (5), and the oxidation catalyst device (3) can be heated by the exhaust gas flowing through the heating gas piping (5).

[0112] 7) In some embodiments, the oxidation catalyst heating system (2) described in any of 2) to 4) above, The aforementioned at least one heating gas pipe (5) is At least one first heating gas piping through which the heating gas flows from one side to the other in the extending direction of the heating gas piping (5) 5A )and, The system includes at least one second heating gas pipe (5B) through which the heating gas flows from the other side toward the one side in the extending direction of the heating gas pipe (5).

[0113] According to the configuration described in 7) above, by setting the flow direction of the exhaust gas flowing through the at least one first heating gas pipe (5A) and the exhaust gas flowing through the at least one second heating gas pipe (5B) to be in opposite directions, it is possible to suppress the uneven distribution of heat transfer from the heating gas flowing through the multiple heating gas pipes (5A, 5B) to the oxidation catalyst device (3) in the direction of extension of the heating gas pipe (5). As a result, the entire oxidation catalyst device (3) can be heated uniformly, and the catalyst heating time required for the oxidation catalyst to perform at the start of use of the oxidation catalyst device (3) can be shortened.

[0114] 8) In some embodiments, the oxidation catalyst heating system (2) described in any of 1) to 7) above, The at least one heating gas piping (5) includes a plurality of heating gas pipings (5) in which a heating gas inlet for introducing the heating gas from the outside into the heating gas piping (5) is connected to a common inlet gas duct (21).

[0115] According to the configuration described in 8) above, by connecting multiple heating gas pipes (5) to a common inlet gas duct (21), the differences in temperature and flow rate of the exhaust gas introduced from the inlet gas duct (21) to the multiple heating gas pipes (5) can be minimized. By minimizing the differences in temperature and flow rate of the exhaust gas introduced to the multiple heating gas pipes (5), thermal energy is uniformly transferred from the heating gas flowing through the multiple heating gas pipes (5) to the oxidation catalyst device (3). This allows the entire oxidation catalyst device (3) to be heated uniformly, and the catalyst heating time required for the oxidation catalyst to perform at its full potential at the start of use of the oxidation catalyst device (3) can be shortened.

[0116] 9) In some embodiments, the oxidation catalyst heating system (2) described in 8) above, The inlet gas duct (21) has an inlet (211) for introducing the heating gas into the interior of the inlet gas duct (21), The plurality of heating gas pipes (5) connected to the inlet gas duct (21) are, Nearby heating gas piping (5C), It includes a distant heating gas piping (5D) connected to the inlet gas duct (21) at a position further away from the inlet (211) than the nearby heating gas piping (5C), An orifice (81) with an opening area smaller than the opening area of ​​the far-side heating gas piping (5D) is provided in either the nearby heating gas piping (5C), the connection point (C1) between the nearby heating gas piping (5C) and the inlet gas duct (21), or the connection point (C2) between the nearby heating gas piping (5C) and the outlet gas duct (22).

[0117] According to the configuration in 9) above, the orifice (81) increases the pressure loss in the nearby heating gas piping (5C), making it easier to introduce exhaust gas from the inlet gas duct (21) to the distant heating gas piping (5D). By minimizing the difference between the flow rate of exhaust gas flowing through the nearby heating gas piping (5C) and the flow rate of exhaust gas flowing through the distant heating gas piping (5D), thermal energy is uniformly transferred from the nearby heating gas piping (5C) and the distant heating gas piping (5D) to the oxidation catalyst device (3). As a result, the entire oxidation catalyst device (3) can be heated uniformly, and the catalyst heating time required for the oxidation catalyst to perform at the start of use of the oxidation catalyst device (3) can be shortened.

[0118] 10) In some embodiments, the oxidation catalyst heating system (2) described in any of 1) to 9) above, The oxidation catalyst device (3) includes a methane oxidation catalyst configured to oxidize the methane contained in the exhaust gas.

[0119] According to the configuration described in 10) above, in order for the methane oxidation catalyst to perform optimally, it is necessary to keep the methane oxidation catalyst (oxidation catalyst device 3) at a relatively high temperature. However, the methane oxidation catalyst can be heated by the heating gas flowing through at least one heating gas pipe (5) described above. This makes it possible to shorten the catalyst heating time required for the methane oxidation catalyst to perform optimally when the oxidation catalyst device (3) is first put into use.

[0120] 11) An internal combustion engine system (1) according to at least one embodiment of the present disclosure is The oxidation catalyst heating system (2) described in 5) above, The internal combustion engine (11) and, An internal combustion engine system (1) comprising a first exhaust gas path switching device (7) configured to switch the path of the exhaust gas discharged from the internal combustion engine (11), The oxidation catalyst device (3) includes a methane oxidation catalyst configured to oxidize the methane contained in the exhaust gas, The internal combustion engine (11) includes a dual-fuel engine capable of operating by switching between a first fuel (FU1) containing methane in its exhaust gas components and a second fuel (FU2) not containing methane in its exhaust gas components. The first exhaust gas path switching device (7) is, The internal combustion engine (11) is configured to guide the exhaust gas discharged from the internal combustion engine (11) to the catalyst casing (4) while the internal combustion engine (11) is operating with the first fuel (FU1) as fuel, and to guide the exhaust gas discharged from the internal combustion engine (11) to the at least one temperature-boosting gas pipe (5) while the internal combustion engine (11) is operating with the second fuel (FU2) as fuel.

[0121] According to the configuration of 11) above, the first exhaust gas path switching device (7) allows exhaust gas discharged from the internal combustion engine (11) to be introduced into the catalyst casing (4) while the internal combustion engine (11) is operating using the first fuel (FU1), thereby oxidizing the methane contained in the exhaust gas by the methane oxidation catalyst. The first exhaust gas path switching device (7) also allows exhaust gas that does not contain methane to be introduced into the at least one heating gas piping (5) while the internal combustion engine (11) is operating using the second fuel (FU2). In this case, exhaust gas discharged from the internal combustion engine (11) that does not require oxidation by the oxidation catalyst device (3) can be used as the heating gas to raise the temperature of the oxidation catalyst device (3). This suppresses the increase in size and complexity of the oxidation catalyst heating system (2) and the internal combustion engine system (1) equipped with the oxidation catalyst heating system (2), and reduces the space occupied by the oxidation catalyst heating system (2) and the internal combustion engine system (1).

[0122] 12) An internal combustion engine system (1) according to at least one embodiment of the present disclosure is The oxidation catalyst heating system (2) described in 6) above, The internal combustion engine (11) and, The aforementioned other internal combustion engine (13), An internal combustion engine system (1) comprising a second exhaust gas path switching device (7A) configured to switch the path of the exhaust gas discharged from the other internal combustion engine (13), The other internal combustion engine (13) includes a dual-fuel engine capable of operating by switching between a first fuel (FU1) containing methane in its exhaust gas components and a second fuel (FU2) not containing methane in its exhaust gas components. The second exhaust gas path switching device (7A) is, The other internal combustion engine (13) is configured to direct the exhaust gas discharged from the other internal combustion engine (13) while it is operating using the second fuel (FU2) to the at least one temperature-boosting gas pipe (5).

[0123] According to the configuration described in 12) above, the second exhaust gas path switching device (7A) allows exhaust gas that does not contain methane in its exhaust gas components, emitted from the other internal combustion engine (13), to be introduced into the at least one heating gas piping (5) while the other internal combustion engine (13) is operating using the second fuel (FU2). In this case, exhaust gas that does not require oxidation by the oxidation catalyst device (3) and is emitted from the other internal combustion engine (13) can be used as the heating gas to heat the oxidation catalyst device (3), thus suppressing the enlargement and complexity of the structure of the oxidation catalyst heating system (2) and the internal combustion engine system (1) equipped with the oxidation catalyst heating system (2), and reducing the space occupied by the oxidation catalyst heating system (2) and the internal combustion engine system (1).

[0124] 13) A method for raising the temperature of an oxidation catalyst apparatus according to at least one embodiment of the present disclosure is: A method for raising the temperature of an oxidation catalyst device (3) configured to oxidize exhaust gas discharged from an internal combustion engine (11), The oxidation catalyst device (3) includes a plurality of oxidation catalyst elements (31), each containing a methane oxidation catalyst configured to oxidize methane contained in the exhaust gas. The internal combustion engine (11) includes a dual-fuel engine capable of operating by switching between a first fuel (FU1) containing methane in its exhaust gas components and a second fuel (FU2) not containing methane in its exhaust gas components. The aforementioned method for raising the temperature of the oxidation catalyst apparatus is: A first operating step involves introducing the exhaust gas discharged from the internal combustion engine (11) into the catalyst casing (4) housing the oxidation catalyst device (3) while the internal combustion engine (11) is operating using the first fuel (FU1), The system includes a second operating step in which, while the internal combustion engine (11) is operating using the second fuel (FU2), the exhaust gas discharged from the internal combustion engine (11) is introduced into at least one heating gas pipe (5) located inside the catalyst casing (4) and positioned between a pair of adjacent oxidation catalyst elements (31) among the plurality of oxidation catalyst elements (31).

[0125] According to the method described in 13) above, in the first operating step, while the internal combustion engine (11) is operating using the first fuel (FU1), exhaust gas discharged from the internal combustion engine (11) is introduced into the catalyst casing (4), thereby oxidizing the methane contained in the exhaust gas components with the methane oxidation catalyst. In the second operating step, while the internal combustion engine (11) is operating using the second fuel (FU2), exhaust gas that does not contain methane in its exhaust gas components discharged from the internal combustion engine (11) can be introduced into the at least one heating gas piping (5). In this case, exhaust gas discharged from the internal combustion engine (11) that does not require oxidation by the oxidation catalyst device (3) can be used as the heating gas to heat the oxidation catalyst device (3), thus suppressing the enlargement and complexity of the equipment for heating the oxidation catalyst device (3) and the internal combustion engine system (1) equipped with said equipment, and reducing the space occupied by said equipment and the internal combustion engine system (1).

[0126] Furthermore, according to the method described in 13) above, the at least one heating gas pipe (5) is positioned between a pair of oxidation catalyst elements (31) that are adjacent to each other inside the catalyst casing (4). This allows the thermal energy of the heating gas flowing through the heating gas pipe (5) to be efficiently transferred to each of the pair of oxidation catalyst elements (31) flanking the heating gas pipe (5). This effectively raises the temperature of the entire oxidation catalyst device (3), and shortens the catalyst heating time required for the oxidation catalyst to perform at the start of use of the oxidation catalyst device (3).

[0127] 14) A method for raising the temperature of an oxidation catalyst apparatus according to at least one embodiment of the present disclosure is: A method for raising the temperature of an oxidation catalyst device (3) configured to oxidize exhaust gas discharged from an internal combustion engine (11), The oxidation catalyst device (3) includes a plurality of oxidation catalyst elements (31), each containing a methane oxidation catalyst configured to oxidize methane contained in the exhaust gas. The aforementioned method for raising the temperature of the oxidation catalyst apparatus is: The system includes an exhaust gas introduction step in which, while the internal combustion engine (11) is stopped, exhaust gas that does not contain methane, discharged from another internal combustion engine (13) different from the internal combustion engine (11), is introduced into at least one heating gas pipe (5) located inside the catalyst casing (4) housing the oxidation catalyst device (3) and positioned between a pair of adjacent oxidation catalyst elements (31) among the plurality of oxidation catalyst elements (31).

[0128] According to the method described in 14) above, the exhaust gas introduction step allows exhaust gas that does not contain methane, emitted from another internal combustion engine (13), to be introduced into the at least one heating gas piping (5) while the internal combustion engine (11) is stopped. In this case, exhaust gas that does not require oxidation by the oxidation catalyst device (3), emitted from another internal combustion engine (13), can be used as the heating gas to heat the oxidation catalyst device (3). This suppresses the need for equipment to heat the oxidation catalyst device (3) and the internal combustion engine system (1) equipped with such equipment, thereby reducing the space occupied by the equipment and the internal combustion engine system (1). Furthermore, according to the method described in 14) above, exhaust gas can be introduced into the at least one heating gas piping (5) even while the internal combustion engine (11) is stopped, and the oxidation catalyst device (3) can be heated by the exhaust gas flowing through the heating gas piping (5).

[0129] Furthermore, according to the method described in 14) above, the at least one heating gas pipe (5) is positioned between a pair of oxidation catalyst elements (31) that are adjacent to each other inside the catalyst casing (4). This allows the thermal energy of the heating gas flowing through the heating gas pipe (5) to be efficiently transferred to each of the pair of oxidation catalyst elements (31) flanking the heating gas pipe (5). This effectively raises the temperature of the entire oxidation catalyst device (3), and shortens the catalyst heating time required for the oxidation catalyst to perform at its full potential when the oxidation catalyst device (3) is first put into use. [Explanation of symbols]

[0130] 1. Internal Combustion Engine System 2. Oxidation catalyst heating system 3,3A Oxidation catalyst device 4.4A Catalyst Casing 5.5E heating gas piping 5A First heating gas piping 5B Second heating gas piping 5C Nearby heating gas piping 5D Remote side heating gas piping 6 partition plates 7. First exhaust gas path switching device 7A Second exhaust gas path switching device 8 Orifice Plate 11,13 Internal combustion engine 12,14 Exhaust gas line 12A First Upstream Exhaust Gas Line 12B First Downstream Exhaust Line 14A Second Upstream Exhaust Line 14B Second Downstream Exhaust Line 21,21C Inlet gas duct 21A First Inlet Gas Duct 21B Second Inlet Gas Duct 22,22C Outlet gas duct 22A First Outlet Gas Duct 22B Second Outlet Gas Duct 23, 25, 27 Exhaust gas branch line 24, 26, 28 Exhaust gas return line 31 Oxidation catalyst element 40 1st interior space 41 Casing body 42. First exhaust gas inlet 43. First exhaust gas outlet 44. First gas duct body 45,47 Partition wall 46. ​​Second gas duct body 51,52 Longitudinal surface 71,71A First shut-off valve 72,72A Second shut-off valve 81 Orifice 400 space FU1 1st fuel FU2 2nd fuel P1, P3, P5 branching point P2,P4,P6 confluence

Claims

1. The exhaust gas line through which exhaust gases emitted from the internal combustion engine flow, A catalyst casing housing an oxidation catalyst device, which includes a plurality of oxidation catalyst elements configured to oxidize the exhaust gas and is installed in the exhaust gas line, An oxidation catalyst heating system comprising: at least one heating gas pipe through which a heating gas for heating the oxidation catalyst device flows, the heating gas pipe being located inside the catalyst casing and positioned between a pair of adjacent oxidation catalyst elements among the plurality of oxidation catalyst elements; The at least one heating gas piping extends along a direction intersecting the flow direction of the exhaust gas flowing inside the catalyst casing, The aforementioned at least one heating gas piping is It has a rectangular cross-sectional shape with a pair of long sides and a pair of short sides, Each of the pair of long sides of the heating gas piping having the long side contacts the pair of oxidation catalyst elements. The aforementioned at least one heating gas piping is When viewed from a first direction, which is the flow direction of the exhaust gas flowing inside the catalyst casing, the catalyst casing includes a plurality of heating gas pipes arranged at intervals in a direction intersecting the extending direction of the heating gas pipe, When viewed from the first direction, the oxidation catalyst heating system is as follows: A plurality of partition plates, each having one end connected to one of a pair of heating gas pipes arranged adjacent to each other in a direction intersecting the extending direction of the heating gas pipe, and further comprising a plurality of partition plates arranged at intervals in the extending direction of the heating gas pipe, Each of the plurality of oxidation catalyst elements is housed in a space partitioned by the pair of heating gas pipes and the plurality of partition plates. Oxidation catalyst heating system.

2. The exhaust gas branch line further branches off from the upstream side of the catalyst casing of the exhaust gas line, The at least one heating gas piping is configured such that the exhaust gas is introduced via the exhaust gas branch line. The oxidation catalyst heating system according to claim 1.

3. The system further comprises another exhaust gas line, different from the aforementioned exhaust gas line, through which exhaust gas emitted from another internal combustion engine, different from the aforementioned internal combustion engine, flows. The at least one heating gas piping is configured such that the exhaust gas is introduced through the other exhaust gas line. The oxidation catalyst heating system according to claim 1.

4. The aforementioned at least one heating gas piping is At least one first heating gas piping through which the heating gas flows from one side to the other in the extending direction of the heating gas piping, The heating gas piping includes at least one second heating gas piping through which the heating gas flows from the other side toward the one side in the extending direction of the heating gas piping, The oxidation catalyst heating system according to claim 1.

5. The at least one heating gas piping includes a plurality of heating gas pipes, each having a heating gas inlet for introducing the heating gas from the outside into the heating gas piping, connected to a common inlet gas duct. The oxidation catalyst heating system according to claim 1.

6. The inlet gas duct has an inlet for introducing the heated gas into the interior of the inlet gas duct. The plurality of heating gas pipes connected to the inlet gas duct are, Nearby heating gas piping, It includes a distant heating gas piping connected to the inlet gas duct at a position further from the inlet than the nearby heating gas piping, An orifice with an opening area smaller than the opening area of ​​the far-side heating gas piping is provided in either the nearby heating gas piping, the connection between the nearby heating gas piping and the inlet gas duct, or the connection between the nearby heating gas piping and the outlet gas duct. The oxidation catalyst heating system according to claim 5.

7. The oxidation catalyst device includes a methane oxidation catalyst configured to oxidize methane contained in the exhaust gas. The oxidation catalyst heating system according to claim 1.

8. The oxidation catalyst heating system according to claim 2, The aforementioned internal combustion engine, An internal combustion engine system comprising: a first exhaust gas path switching device configured to switch the path of the exhaust gas discharged from the internal combustion engine, The oxidation catalyst device includes a methane oxidation catalyst configured to oxidize methane contained in the exhaust gas, The internal combustion engine includes a dual-fuel engine capable of operating by switching between a first fuel containing methane in its exhaust gas components and a second fuel not containing methane in its exhaust gas components. The first exhaust gas path switching device is The internal combustion engine is configured to guide the exhaust gas discharged from the internal combustion engine to the catalyst casing while the internal combustion engine is operating with the first fuel, and to guide the exhaust gas discharged from the internal combustion engine to the at least one heating gas piping while the internal combustion engine is operating with the second fuel. Internal combustion engine system.

9. The oxidation catalyst heating system according to claim 3, The aforementioned internal combustion engine, The aforementioned other internal combustion engines, An internal combustion engine system comprising: a second exhaust gas path switching device configured to switch the path of the exhaust gas discharged from the other internal combustion engine, The aforementioned other internal combustion engine includes a dual-fuel engine capable of operating by switching between a first fuel containing methane in its exhaust gas components and a second fuel not containing methane in its exhaust gas components. The second exhaust gas path switching device is The other internal combustion engine is configured to guide the exhaust gas discharged from the other internal combustion engine while it is operating using the second fuel to the at least one heating gas piping, Internal combustion engine system.

10. A method for raising the temperature of an oxidation catalyst device configured to oxidize exhaust gas discharged from an internal combustion engine, The oxidation catalyst device includes a plurality of oxidation catalyst elements, each containing a methane oxidation catalyst configured to oxidize methane contained in the exhaust gas. The internal combustion engine includes a dual-fuel engine capable of operating by switching between a first fuel containing methane in its exhaust gas components and a second fuel not containing methane in its exhaust gas components. The aforementioned method for raising the temperature of the oxidation catalyst apparatus is: A first operating step involves introducing the exhaust gas discharged from the internal combustion engine into a catalyst casing housing the oxidation catalyst device while the internal combustion engine is operating using the first fuel, The system includes a second operating step in which, while the internal combustion engine is operating using the second fuel, exhaust gas discharged from the internal combustion engine is introduced into at least one heating gas pipe located inside the catalyst casing and between a pair of adjacent oxidation catalyst elements among the plurality of oxidation catalyst elements. A method for increasing the temperature of an oxidation catalyst apparatus.

11. A method for raising the temperature of an oxidation catalyst device configured to oxidize exhaust gas discharged from an internal combustion engine, The oxidation catalyst device includes a plurality of oxidation catalyst elements, each containing a methane oxidation catalyst configured to oxidize methane contained in the exhaust gas. The aforementioned method for raising the temperature of the oxidation catalyst apparatus is: The system includes an exhaust gas introduction step in which, while the internal combustion engine is stopped, exhaust gas that does not contain methane, emitted from another internal combustion engine different from the one described above, is introduced into at least one heating gas pipe located inside the catalyst casing housing the oxidation catalyst device and positioned between a pair of adjacent oxidation catalyst elements among the plurality of oxidation catalyst elements. A method for increasing the temperature of an oxidation catalyst apparatus.

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